Cell Circuit and Layout with Linear Finfet Structures

ABSTRACT

A cell circuit and corresponding layout is disclosed to include linear-shaped diffusion fins defined to extend over a substrate in a first direction so as to extend parallel to each other. Each of the linear-shaped diffusion fins is defined to project upward from the substrate along their extent in the first direction. A number of gate level structures are defined to extend in a conformal manner over some of the number of linear-shaped diffusion fins. Portions of each gate level structure that extend over any of the linear-shaped diffusion fins extend in a second direction that is substantially perpendicular to the first direction. Portions of each gate level structure that extend over any of the linear-shaped diffusion fins form gate electrodes of a corresponding transistor. The diffusion fins and gate level structures can be placed in accordance with a diffusion fin virtual grate and a gate level virtual grate, respectively.

CLAIM OF PRIORITY

This application is a continuation application under 35 U.S.C. 120 of prior U.S. application Ser. No. 12/775,429, filed on May 6, 2010, which claims priority under 35 U.S.C. 119(e) to U.S. Provisional Patent Application No. 61/176,058, filed May 6, 2009. The disclosure of each above-identified patent application is incorporated herein by reference in its entirety for all purposes.

BACKGROUND

It is known that optical lithography has reached the end of its capability at the 193 nm light wavelength and 1.35 numerical aperture (NA) immersion system. The minimum straight line resolution capability of this equipment is approximately 40 nm with an approximate 80 nm feature-to-feature pitch. A feature-to-feature pitch requirement lower than about 80 nm would require multiple patterning steps for a given structure type within a given chip level. Also, line end resolution becomes more challenging as lithography is pushed toward its resolution limits. One solution to line end shortening is to add a subsequent patterning step to cut features so as to form the line ends. Such line end cutting allows two line ends to be placed in closer proximity, and therefore may improve overall feature placement density, but at the cost of an additional patterning step. It should be understood that the added lithography steps for multiple patterning and/or line end cutting increases manufacturing cost, possibly to the point where any improvement in feature placement density is financially negated.

In semiconductor device layout, a typical metal line pitch at the 32 nm critical dimension is approximately 100 nm. In order to achieve the cost benefit of feature scaling, a scaling factor of 0.7 to 0.75 is desirable. The scaling factor of about 0.75 to reach the 22 nm critical dimension would require a metal line pitch of about 75 nm, which is below the capability of current single exposure lithography systems and technology.

SUMMARY

In one embodiment, a cell circuit of a semiconductor device is disclosed. The cell circuit includes a substrate, and a number of linear-shaped diffusion fins defined to extend over the substrate in a first direction so as to extend parallel to each other. Each of the number of linear-shaped diffusion fins is defined to project upward from the substrate along their extent in the first direction. The cell circuit also includes a number of gate level structures defined to extend in a conformal manner over some of the number of linear-shaped diffusion fins. Portions of each gate level structure that extend over any of the number of linear-shaped diffusion fins extend in a second direction that is substantially perpendicular to the first direction. Portions of each gate level structure that extend over any of the number of linear-shaped diffusion fins form gate electrodes of a corresponding transistor.

In one embodiment, a semiconductor device cell layout is disclosed. The cell layout includes a diffusion level layout and a gate level layout. The diffusion level layout includes a number of diffusion fin layout shapes defined to extend in only a first direction across the cell layout so as to extend parallel to each other. Each of the number of diffusion fin layout shapes corresponds to diffusion fin structures defined to project upward from a substrate along their extent in the first direction. The gate level layout includes a number of gate level layout shapes defined to extend in a second direction across the cell layout that is substantially perpendicular to the first direction. Each of the gate level layout shapes corresponds to gate level structures defined to extend in a conformal manner over some of the diffusion fin structures that correspond to the diffusion fin layout shapes. Portions of each gate level structure that extend over any of the diffusion fin structures form gate electrodes of a corresponding transistor.

Other aspects and advantages of the invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B show a layout view of a finfet transistor, in accordance with one embodiment of the present invention;

FIG. 2A shows an exemplary cell layout incorporating finfet transistors, in accordance with one embodiment of the present invention;

FIG. 2B shows a vertical cross-section view B-B as called out in FIG. 2A, in accordance with one embodiment of the present invention;

FIG. 2C shows a vertical cross-section view C-C as called out in FIG. 2A, in accordance with one embodiment of the present invention;

FIG. 3A shows an example of gate electrode tracks defined within the restricted gate level layout architecture, in accordance with one embodiment of the present invention; and

FIG. 3B shows the exemplary restricted gate level layout architecture of FIG. 3A with a number of exemplary gate level features defined therein, in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail in order not to unnecessarily obscure the present invention.

A “finfet” is a transistor constructed from a vertical silicon island. The finfet transistor can also be referred to as a tri-gate transistor. FIGS. 1A and 1B show a layout view of a finfet transistor 100, in accordance with one embodiment of the present invention. The finfet transistor 100 is constructed from a diffusion island 102 and a gate electrode layer 104. The diffusion island 102 projects vertically upward from a substrate 105, as shown in FIG. 1B. A gate oxide layer 106 is disposed between the diffusion island 102 and the gate electrode layer 104. The diffusion island 102 can be doped to form either a p-type transistor or an n-type transistor. The portion of the gate electrode layer 104 that covers the diffusion island 102 forms the gate electrode of the finfet transistor 100.

Therefore, the gate electrode of the finfet transistor 100 exists on three sides of the diffusion island 102, thereby providing for control of the finfet transistor channel from three sides, as opposed to from one side as in a non-finfet transistor.

Transistor scaling has slowed below the 45 nanometers (nm) critical dimension due to gate oxide limitations and/or source/drain leakage scaling issues. The finfet transistor mitigates these issues by controlling the channel of the finfet transistor from three sides. The increased electrical fields in the channel of the finfet transistor improve the relationship between I-on (on drive current) and I-off (sub-threshold leakage current). Finfet transistors can be employed at the 22 nm critical dimension and below. However, due to their vertical projection, finfet transistors can have restricted placement in various circuit layouts. For instance, there can be a required finfet-to-finfet minimum spacing and/or a required finfet-to-finfet minimum pitch, among other restrictions. Embodiments are disclosed herein for cell layouts that utilize finfet transistors in a manner which complements layout scaling.

FIG. 2A shows an exemplary cell layout incorporating finfet transistors, in accordance with one embodiment of the present invention. The cell layout is defined by a cell width W and a cell height H. The cell layout includes a diffusion level within which a number of diffusion islands 102 are defined for subsequent formation of finfet transistors and associated connections. The diffusion islands 102 are also referred to as diffusion fins 102. In an as-drawn layout state, the diffusion fins 102 are linear-shaped. The diffusion fins 102 are oriented to be parallel to each other such that their lengths extend in the direction of the cell width W.

In one embodiment, the diffusion fins 102 are placed along a number of diffusion tracks 201A-201H. The diffusion tracks 201A-201H represent virtual lines that extend in the direction of the cell width W and are equally spaced at a fixed pitch. The pitch of the diffusion tracks 201A-201H is related to the cell height H, such that the diffusion track pitch can be continued across cell boundaries. Therefore, the diffusion fins 102 for multiple neighboring cells will be placed in accordance with a common global set of equally spaced diffusion tracks, thereby facilitating chip level manufacturing of the diffusion fins 102 in multiple cells.

It should be understood that the diffusion fins 102 can be placed as needed, so long as they are placed in accordance with the diffusion tracks 201A-201H which have the controlled spatial relationship with the cell height H. Therefore, some diffusion tracks 201A-201H may not have a diffusion fin 102 placed thereon. Also, portions of some diffusion tracks 201A-201H may be vacant with regard to diffusion fin 102 placement. In other words, some diffusion tracks 201A-201H will have one or more portions occupied by diffusion fins 102 and one or more portions not occupied by diffusion fins 102.

The cell layout also includes a number of linear-shaped gate electrode structures 104. The linear-shaped gate electrode structures 104 extend in a substantially perpendicular direction to the diffusion fins 102, i.e., in the direction of the cell height H. The linear-shaped gate electrode structures 104 wrap over the diffusion fins 102 to form gate electrodes of finfet transistors. It should be understood that an appropriate gate oxide material is disposed between the diffusion fins 102 and the gate electrode structures 104 formed thereover.

In one embodiment, the linear-shaped gate electrode structures 104 are placed in accordance with a gate level virtual grate defined by a set of parallel equally spaced virtual lines 202A-202T that extend in the direction of the cell height H. The set of virtual lines 202A-202T of the gate level virtual grate are spaced at a fixed gate pitch. In one embodiment, the gate pitch is related to the cell width W, such that the gate pitch can be continued across cell boundaries. Therefore, the gate electrode structures 104 for multiple neighboring cells will be placed in accordance with a common global set of equally spaced gate level virtual grate lines, thereby facilitating chip level manufacturing of the linear-shaped gate electrode structures 104 in multiple cells.

It should be understood that some of the gate level virtual grate lines 202A-202T may be occupied by gate electrode structures 104, while others of the gate level virtual grate lines 202A-202T are left vacant. Also, along a given gate level virtual grate line 202A-202T, one or more linear-shaped gate electrode structures 104 can be placed as needed and spaced apart as needed.

The cell layout also includes a number of linear-shaped local interconnect structures 203. The local interconnect structures 203 are oriented parallel to the gate electrode structures 104. In one embodiment, placement of the local interconnect structures 203 is defined to be out of phase from placement of the gate electrode structures 104 by one-half of the gate pitch. Thus, in this embodiment, each local interconnect structure 203 is centered between its neighboring gate level virtual grate lines 202A-202T. And, if its neighboring gate level virtual grate lines 202A-202T are occupied by gate electrode structures 104, the local interconnect structure 203 will be correspondingly centered between the neighboring gate electrode structures 104. Therefore, in this embodiment, adjacently placed local interconnect structures 203 will have a center-to-center spacing equal to the gate pitch.

In one embodiment, the cell layout also includes a number of linear-shaped metal 1 (M1) interconnect structures 205. The M1 interconnect structures 205 are oriented parallel to the diffusion fins 102 and perpendicular to the gate electrode structures 104. In one embodiment, placement of the M1 interconnect structures 205 is defined to be out of phase from placement of the diffusion fins 102 by one-half of the diffusion track 201A-201H pitch. Thus, in this embodiment, each M1 interconnect structure 205 is centered between its neighboring diffusion tracks 201A-201H. And, if its neighboring diffusion tracks 201A-201H are occupied by diffusion fins 102, the M1 interconnect structure 205 will be correspondingly centered between its neighboring diffusion fins 102, albeit within a higher chip level. Therefore, in this embodiment, adjacently placed M1 interconnect structures 205 will have a center-to-center spacing equal to the diffusion track pitch. In one embodiment, the M1 interconnect structure 205 pitch, and hence the diffusion track pitch, is set at the single exposure lithographic limit, e.g., 80 nm for 193 nm wavelength light and 1.35 NA. In this embodiment, no double exposure lithography, i.e., multiple patterning, is required to manufacture the M1 interconnect structures 205.

The cell layout also includes a number of contacts 207 defined to connect various M1 interconnect structures 205 to various local interconnect structures 203 and gate electrode structures 104, thereby providing electrical connectivity between the various finfet transistors as necessary to implement the logic function of the cell. In one embodiment, the contacts 205 are defined to satisfy single exposure lithographic limits. For example, in one embodiment, layout features to which the contacts 207 are to connect are sufficiently separated to enable single exposure manufacture of the contacts 207. For instance, the M1 interconnect structures 205 are defined such that their line ends which are to receive contacts 207 are sufficiently separated from neighboring M1 interconnect structure 205 line ends which are also to receive contacts 207, such that a spatial proximity between the contacts 207 is sufficiently large to enable single exposure lithography of the contacts 207. In one embodiment, neighboring contacts 207 are separated from each other by at least 1.5 times the gate pitch. It should be appreciated that line end cutting and the associated increased expense of double exposure lithography can be eliminated by sufficiently separating opposing line ends of the M1 interconnect structures 205.

As previously mentioned, the cell height H and diffusion track pitch, i.e., diffusion fin pitch, are related. In one embodiment, the cell height H is an integer multiple of the diffusion track pitch. The cell layout techniques described herein can be used to reduce the cell height H by the approximate difference between the single exposure lithographic capability and an applicable scaling requirement. For example, consider that the cell height

H is based on the single exposure straight line lithographic limit, e.g., 80 nm diffusion fin pitch. Therefore, the diffusion track pitch of the cell cannot be scaled down further without incurring the cost of multiple patterning. However, the cell layout techniques described herein can be utilized to scale down the overall size of the cell layout while maintaining the single exposure straight line lithographic limit with regard to the diffusion track pitch.

For example, if a 9 diffusion track cell was used at 32 nm, then a scaled down version of the cell having 8 tracks at 22 nm is created to provide the overall cell layout scaling requirements. Specifically, the M1 interconnect structure 205 layout of the cell is drawn in fewer tracks, e.g., 8 tracks rather than 9 tracks, and the opposing line ends of the M1 interconnect structures 205 are arranged so that the single exposure lithography design rules can be satisfied. Reduction of the cell height H by one diffusion track can add up to significant layout area savings across the chip.

FIG. 2B shows a vertical cross-section view B-B as called out in FIG. 2A, in accordance with one embodiment of the present invention. The diffusion fins 102 are shown to project upward from the substrate 105. An insulating material 211, such as an oxide, is disposed between and around the diffusion fins 102 to provide structural support and electrical insulation. The local interconnect feature 203 is shown to extend perpendicular to the diffusion fins 102 and across the tops of the diffusion fins 102 so as to establish electrical connections between the local interconnect feature 203 and each of the diffusion fins 102. The contact 207 is shown to extend vertically through the layout to electrically connect the M1 interconnect structure 205 to the local interconnect structure 203. The contact 207 and M1 interconnect structure 205 are also surrounded by the insulating material 211, which again provides structural support and electrical insulation. It should be appreciated that the M1 interconnect structure 205 is positioned in a centered manner with respect to its neighboring underlying diffusion fins 102, as discussed above.

FIG. 2C shows a vertical cross-section view C-C as called out in FIG. 2A, in accordance with one embodiment of the present invention. The diffusion fin 102 is shown to project upward from the substrate 105. The gate oxide material 106 is disposed conformally over the diffusion fin 102. The gate electrode structure 104 is shown to extend perpendicular to the diffusion fin 102 and conformally over the diffusion fin 102. The contact 207 is shown to extend vertically to electrically connect the M1 interconnect structure 205 to the gate electrode structure 104. The insulating material 211, such as an oxide, is disposed over and around the gate electrode structure 104, the contact 207, and the M1 interconnect structure 205 to provide structural support and electrical insulation.

It should be understood that the relative sizes of the different layout features as shown in FIGS. 2A-2C are exemplary, and in no way limit the principles of the present invention as disclosed herein. For example, in other embodiments, the M1 power lines shown at the top and bottom of the cell layout in FIG. 2A can be of different width, e.g., larger width, than the M1 lines within an interior of the cell. Additionally, the relative vertical heights of the layout features as shown in the cross-sections of FIGS. 2B and 2C can vary from what is depicted therein. For example, in FIG. 2C, the gate electrode 104 may extend further vertically than what is shown.

Restricted Gate Level Layout Architecture

The cell layout incorporating finfet transistors, as discussed above, can implemented a restricted gate level layout architecture. For the gate level, a number of parallel virtual lines are defined to extend across the layout. These parallel virtual lines are referred to as gate electrode tracks, as they are used to index placement of gate electrodes of various transistors within the layout. In one embodiment, such as the cell layout discussed above with regard to FIG. 2A, the parallel virtual lines which form the gate electrode tracks are defined by a perpendicular spacing therebetween equal to a specified gate electrode pitch. Therefore, placement of gate electrode segments on the gate electrode tracks corresponds to the specified gate electrode pitch. In another embodiment the gate electrode tracks can be spaced at variable pitches greater than or equal to a specified gate electrode pitch.

FIG. 3A shows an example of gate electrode tracks 301A-301E defined within the restricted gate level layout architecture, in accordance with one embodiment of the present invention. Gate electrode tracks 301A-301E are formed by parallel virtual lines that extend across the gate level layout of the chip, with a perpendicular spacing therebetween equal to a specified gate electrode pitch 307.

Within the restricted gate level layout architecture, a gate level feature layout channel is defined about a given gate electrode track so as to extend between gate electrode tracks adjacent to the given gate electrode track. For example, gate level feature layout channels 301A-1 through 301E-1 are defined about gate electrode tracks 301A through 301E, respectively. It should be understood that each gate electrode track has a corresponding gate level feature layout channel. Also, for gate electrode tracks positioned adjacent to an edge of a prescribed layout space, e.g., adjacent to a cell boundary, the corresponding gate level feature layout channel extends as if there were a virtual gate electrode track outside the prescribed layout space, as illustrated by gate level feature layout channels 301A-1 and 301E-1. It should be further understood that each gate level feature layout channel is defined to extend along an entire length of its corresponding gate electrode track. Thus, each gate level feature layout channel is defined to extend across the gate level layout within the portion of the chip to which the gate level layout is associated.

Within the restricted gate level layout architecture, gate level features associated with a given gate electrode track are defined within the gate level feature layout channel associated with the given gate electrode track. A contiguous gate level feature can include both a portion which defines a gate electrode of a transistor, i.e., of a finfet transistor as disclosed herein, and a portion that does not define a gate electrode of a transistor. Thus, a contiguous gate level feature can extend over both a diffusion region, i.e., diffusion fin, and a dielectric region of an underlying chip level.

In one embodiment, each portion of a gate level feature that forms a gate electrode of a transistor is positioned to be substantially centered upon a given gate electrode track. Furthermore, in this embodiment, portions of the gate level feature that do not form a gate electrode of a transistor can be positioned within the gate level feature layout channel associated with the given gate electrode track. Therefore, a given gate level feature can be defined essentially anywhere within a given gate level feature layout channel, so long as gate electrode portions of the given gate level feature are centered upon the gate electrode track corresponding to the given gate level feature layout channel, and so long as the given gate level feature complies with design rule spacing requirements relative to other gate level features in adjacent gate level layout channels. Additionally, physical contact is prohibited between gate level features defined in gate level feature layout channels that are associated with adjacent gate electrode tracks.

FIG. 3B shows the exemplary restricted gate level layout architecture of FIG. 3A with a number of exemplary gate level features 309-323 defined therein, in accordance with one embodiment of the present invention. The gate level feature 309 is defined within the gate level feature layout channel 301A-1 associated with gate electrode track 301A. The gate electrode portions of gate level feature 309 are substantially centered upon the gate electrode track 301A. Also, the non-gate electrode portions of gate level feature 309 maintain design rule spacing requirements with gate level features 311 and 313 defined within adjacent gate level feature layout channel 301B-1. Similarly, gate level features 311-323 are defined within their respective gate level feature layout channel, and have their gate electrode portions substantially centered upon the gate electrode track corresponding to their respective gate level feature layout channel. Also, it should be appreciated that each of gate level features 311-323 maintains design rule spacing requirements with gate level features defined within adjacent gate level feature layout channels, and avoids physical contact with any another gate level feature defined within adjacent gate level feature layout channels.

A gate electrode corresponds to a portion of a respective gate level feature that extends over a diffusion structure, i.e., over a diffusion fin, wherein the respective gate level feature is defined in its entirety within a gate level feature layout channel. Each gate level feature is defined within its gate level feature layout channel without physically contacting another gate level feature defined within an adjoining gate level feature layout channel. As illustrated by the example gate level feature layout channels 301A-1 through 301E-1 of FIG. 3B, each gate level feature layout channel is associated with a given gate electrode track and corresponds to a layout region that extends along the given gate electrode track and perpendicularly outward in each opposing direction from the given gate electrode track to a closest of either an adjacent gate electrode track or a virtual gate electrode track outside a layout boundary.

Some gate level features may have one or more contact head portions defined at any number of locations along their length. A contact head portion of a given gate level feature is defined as a segment of the gate level feature having a height and a width of sufficient size to receive a gate contact structure. In this instance, “width” is defined across the substrate in a direction perpendicular to the gate electrode track of the given gate level feature, and “height” is defined across the substrate in a direction parallel to the gate electrode track of the given gate level feature. The gate level feature width and height may or may not correspond to the cell width W and cell height H, depending on the orientation of the gate level features within the cell. It should be appreciated that a contact head of a gate level feature, when viewed from above, can be defined by essentially any layout shape, including a square or a rectangle. Also, depending on layout requirements and circuit design, a given contact head portion of a gate level feature may or may not have a gate contact defined thereabove.

A gate level of the various embodiments disclosed herein is defined as a restricted gate level, as discussed above. Some of the gate level features form gate electrodes of transistor devices. Others of the gate level features can form conductive segments extending between two points within the gate level. Also, others of the gate level features may be non-functional with respect to integrated circuit operation. It should be understood that the each of the gate level features, regardless of function, is defined to extend across the gate level within their respective gate level feature layout channels without physically contacting other gate level features defined with adjacent gate level feature layout channels.

In one embodiment, the gate level features are defined to provide a finite number of controlled layout shape-to-shape lithographic interactions which can be accurately predicted and optimized for in manufacturing and design processes. In this embodiment, the gate level features are defined to avoid layout shape-to-shape spatial relationships which would introduce adverse lithographic interaction within the layout that cannot be accurately predicted and mitigated with high probability. However, it should be understood that changes in direction of gate level features within their gate level layout channels are acceptable when corresponding lithographic interactions are predictable and manageable.

It should be understood that each of the gate level features, regardless of function, is defined such that no gate level feature along a given gate electrode track is configured to connect directly within the gate level to another gate level feature defined along a different gate electrode track without utilizing a non-gate level feature. Moreover, each connection between gate level features that are placed within different gate level layout channels associated with different gate electrode tracks is made through one or more non-gate level features, which may be defined in higher interconnect levels, i.e., through one or more interconnect levels above the gate level, or by way of local interconnect features at or below the gate level.

Exemplary Embodiments

In one embodiment, a cell circuit of a semiconductor device is disclosed. The cell circuit includes a substrate and a number of linear-shaped diffusion fins defined to extend over the substrate in a first direction, so as to extend parallel to each other. Each of the number of linear-shaped diffusion fins is defined to project upward from the substrate along their extent in the first direction. In one embodiment, each of the number of linear-shaped diffusion fins is formed from a doped silicon-based material to form either a p-type or an n-type transistor diffusion region.

The cell circuit also includes a number of gate level structures defined to extend in a conformal manner over some of the number of linear-shaped diffusion fins. Portions of each gate level structure that extend over any of the number of linear-shaped diffusion fins extend in a second direction that is substantially perpendicular to the first direction. Portions of each gate level structure that extend over any of the number of linear-shaped diffusion fins form gate electrodes of a corresponding transistor. In one embodiment, each of the number of gate level structures is formed from an electrically conductive material.

In one embodiment, the number of linear-shaped diffusion fins are positioned on diffusion tracks that correspond to virtual lines of a diffusion fin virtual grate. The diffusion tracks extend in the first direction over the substrate. In a particular embodiment, the diffusion tracks are positioned based on a fixed diffusion track pitch. The fixed diffusion track pitch corresponds to an equal perpendicular spacing between adjacent diffusion tracks. In one instance of this particular embodiment, a size of the fixed diffusion track pitch is set at a single exposure lithographic limit.

Also, in one embodiment, the first direction corresponds to a width direction of the cell circuit. In this embodiment, the fixed diffusion track pitch is related to a height of the cell circuit, such that a continuity of the fixed diffusion track pitch is maintained across boundaries of the cell circuit to form a global set of equally spaced diffusion tracks across a group of neighboring cell circuits. In one instance of this embodiment, the height of the cell circuit is an integer multiple of the fixed diffusion track pitch.

The number of linear-shaped diffusion fins are positioned on diffusion tracks as needed for cell circuit functionality. In various embodiments, some diffusion tracks are partially filled with linear-shaped diffusion fins, some diffusion tracks are completely filled with linear-shaped diffusion fins, some diffusion tracks are vacant and do not have a linear-shaped diffusion fin positioned thereon, or any combination thereof.

In one embodiment, the portions of the gate level structures that extend over any of the number of linear-shaped diffusion fins are positioned on gate electrode tracks that correspond to virtual lines of a gate level virtual grate. The gate electrode tracks extend in the second direction over the substrate. In one embodiment, the gate electrode tracks are positioned based on a fixed gate electrode track pitch. The fixed gate electrode track pitch corresponds to an equal perpendicular spacing between adjacent gate electrode tracks.

In one embodiment, the second direction corresponds to a height direction of the cell circuit. The fixed gate electrode track pitch can be related to a width of the cell circuit, such that a continuity of the fixed gate electrode track pitch is maintained across boundaries of the cell circuit to form a global set of equally spaced gate electrode tracks across a group of neighboring cell circuits. In one embodiment, the width of the cell circuit is an integer multiple of the fixed gate electrode track pitch.

The gate level structures are positioned on gate electrode tracks as needed for cell circuit functionality. In various embodiments, some gate electrode tracks are partially filled with gate level structures, some gate electrode tracks are completely filled with gate level structures, some gate electrode tracks are vacant and do not have a gate level structure positioned thereon, or any combination thereof.

Also, in another embodiment, the gate level structures are positioned to maximally fill gate electrode tracks. In this embodiment, breaks are defined between multiple gate level structures along individual gate electrode tracks as needed for cell circuit functionality. In one instance of this embodiment, the breaks defined between multiple gate level structures along individual gate electrode tracks are uniform in size through the cell circuit.

The cell circuit can also include a number of local interconnect structures defined between neighboring gate level structures so as to extend in the second direction parallel to the neighboring gate level structures. The number of local interconnect structures are formed of an electrically conductive material. Also, the number of local interconnect structures are formed at or below a gate level of the cell circuit. Additionally, the cell circuit can include a number of higher level interconnect structures defined in an interconnect level above a gate level of the cell circuit. In one embodiment, the number of higher level interconnect structures are linear-shaped and extend in the first direction. In another embodiment, the number of higher level interconnect structures are unrestricted with regard to shape and are formed as necessary for circuit functionality. The cell circuit can also include a number of contact structures, and any other type of structure previously discussed with regard to the examples of FIGS. 2A-2C.

In another embodiment, a semiconductor device cell layout is disclosed. This embodiment is essentially a layout of the cell circuit embodiment discussed above. Therefore, any features discussed above with regard to the cell circuit embodiment can be represented within this cell layout embodiment. The cell layout includes a diffusion level layout and a gate level layout. The diffusion level layout includes a number of diffusion fin layout shapes defined to extend in only a first direction across the cell layout, so as to extend parallel to each other. The number of diffusion fin layout shapes correspond to diffusion fin structures defined to project upward from a substrate along their extent in the first direction.

In one embodiment, the diffusion fin layout shapes are positioned on diffusion tracks that correspond to virtual lines of a diffusion fin virtual grate. The diffusion tracks extend in the first direction across the cell layout. In one embodiment, the diffusion tracks are positioned based on a fixed diffusion track pitch. The fixed diffusion track pitch corresponds to an equal perpendicular spacing between adjacent diffusion tracks. In one embodiment, the first direction corresponds to a width direction of the cell layout. In this embodiment, the fixed diffusion track pitch is related to a height of the cell layout, such that a continuity of the fixed diffusion track pitch is maintained across boundaries of the cell layout to form a global set of equally spaced diffusion tracks across a group of neighboring cell layouts. In one instance of this embodiment, the height of the cell layout is an integer multiple of the fixed diffusion track pitch.

The gate level layout of the cell layout includes a number of gate level layout shapes defined to extend in a second direction across the cell layout that is substantially perpendicular to the first direction. The gate level layout shapes correspond to gate level structures defined to extend in a conformal manner over some of the diffusion fin structures which correspond to the diffusion fin layout shapes. Portions of each gate level structure that extend over any of the diffusion fin structures form gate electrodes of a corresponding transistor.

In one embodiment, portions of the gate level layout shapes that extend over any of the diffusion fin layout shapes are positioned on gate electrode tracks that correspond to virtual lines of a gate level virtual grate. The gate electrode tracks extend in the second direction across the cell layout, i.e., perpendicular to the first direction. In one embodiment, the gate electrode tracks are positioned based on a fixed gate electrode track pitch. The fixed gate electrode track pitch corresponds to an equal perpendicular spacing between adjacent gate electrode tracks. In one embodiment, the second direction corresponds to a height direction of the cell layout. In this embodiment, the fixed gate electrode track pitch is related to a width of the cell layout, such that a continuity of the fixed gate electrode track pitch is maintained across boundaries of the cell layout to form a global set of equally spaced gate electrode tracks across a group of neighboring cell layouts. In one instance of this embodiment, the width of the cell layout is an integer multiple of the fixed gate electrode track pitch. It should be understood that the cell layout can also include a number of additional layout shapes and levels corresponding to other circuit structures, including any other type of circuit structure previously discussed with regard to the examples of FIGS. 2A-2C.

It should be understood that any cell layout incorporating finfet transistors as disclosed herein can be stored in a tangible form, such as in a digital format on a computer readable medium. For example, a given cell layout can be stored in a layout data file, and can be selectable from one or more libraries of cells. The layout data file can be formatted as a GDS II (Graphic Data System) database file, an OASIS (Open Artwork System

Interchange Standard) database file, or any other type of data file format suitable for storing and communicating semiconductor device layouts. Also, multi-level layouts of a cell incorporating finfet transistors as disclosed herein can be included within a multi-level layout of a larger semiconductor device. The multi-level layout of the larger semiconductor device can also be stored in the form of a layout data file, such as those identified above.

Also, the invention described herein can be embodied as computer readable code on a computer readable medium. For example, the computer readable code can include a layout data file within which a layout of a cell incorporating finfet transistors as disclosed herein is stored. The computer readable code can also include program instructions for selecting one or more layout libraries and/or cells that include finfet transistors as disclosed herein. The layout libraries and/or cells can also be stored in a digital format on a computer readable medium.

The computer readable medium mentioned herein is any data storage device that can store data which can thereafter be read by a computer system. Examples of the computer readable medium include hard drives, network attached storage (NAS), read-only memory, random-access memory, CD-ROMs, CD-Rs, CD-RWs, magnetic tapes, and other optical and non-optical data storage devices. Multiple computer readable media distributed within a network of coupled computer systems can also be used to store respective portions of the computer readable code such that the computer readable code is stored and executed in a distributed fashion within the network.

It should be further understood that any cell layout incorporating finfet transistors as disclosed herein can be manufactured as part of a semiconductor device or chip. In the fabrication of semiconductor devices such as integrated circuits, memory cells, and the like, a series of manufacturing operations are performed to define features on a semiconductor wafer. The wafer includes integrated circuit devices in the form of multi-level structures defined on a silicon substrate. At a substrate level, transistor devices with diffusion regions and/or diffusion fins are formed. In subsequent levels, interconnect metallization lines are patterned and electrically connected to the transistor devices to define a desired integrated circuit device. Also, patterned conductive layers are insulated from other conductive layers by dielectric materials.

While this invention has been described in terms of several embodiments, it will be appreciated that those skilled in the art upon reading the preceding specifications and studying the drawings will realize various alterations, additions, permutations and equivalents thereof. Therefore, it is intended that the present invention includes all such alterations, additions, permutations, and equivalents as fall within the true spirit and scope of the invention. 

What is claimed is:
 1. An integrated circuit, comprising: a substrate; a first diffusion fin defined to extend over the substrate; a first local interconnect structure formed to electrically connect the first diffusion fin to a first power line; a second diffusion fin defined to extend over the substrate; a second local interconnect structure formed to electrically connect the second diffusion fin to a second power line; a third local interconnect structure formed to extend over and physically connect with each of the first diffusion fin and the second diffusion fin; and a gate level structure formed to extend over and physically connect with each of the first diffusion fin and the second diffusion fin, the gate level structure positioned to physically connect with the first diffusion fin at a location between the first local interconnect structure and the third local interconnect structure, the gate level structure positioned to physically connect with the second diffusion fin at a location between the second local interconnect structure and the third local interconnect structure.
 2. The integrated circuit as recited in claim 1, wherein each of the first diffusion fin and the second diffusion fin is linear-shaped and is defined to extend lengthwise over the substrate in a first direction so as to extend parallel to each other.
 3. The integrated circuit as recited in claim 2, wherein the gate level structure is linear-shaped and is defined to extend lengthwise in a second direction perpendicular to the first direction.
 4. The integrated circuit as recited in claim 3, wherein the first local interconnect structure is linear-shaped and is defined to extend lengthwise in the second direction, and wherein the second local interconnect structure is linear-shaped and is defined to extend lengthwise in the second direction, and wherein the third local interconnect structure is linear-shaped and is defined to extend lengthwise in the second direction.
 5. The integrated circuit as recited in claim 4, wherein the gate level structure is substantially centered in the first direction between the first local interconnect structure and the third local interconnect structure.
 6. The integrated circuit as recited in claim 5, wherein the gate level structure is substantially centered in the first direction between the second local interconnect structure and the third local interconnect structure.
 7. The integrated circuit as recited in claim 6, further comprising: a first contact structure positioned to provide electrical connection between the first local interconnect structure and the first power line.
 8. The integrated circuit as recited in claim 7, further comprising: a second contact structure positioned to provide electrical connection between the second local interconnect structure and the second power line.
 9. The integrated circuit as recited in claim 8, further comprising: a third contact structure positioned to provide electrical connection between the gate level structure and an interconnect structure positioned at a higher level than the gate level structure.
 10. The integrated circuit as recited in claim 9, wherein the first diffusion fin is a p-type diffusion fin, and wherein the second diffusion fin is an n-type diffusion fin.
 11. The integrated circuit as recited in claim 9, further comprising: a third diffusion fin of linear shape, the third diffusion fin defined to extend lengthwise over the substrate in the first direction, wherein the first local interconnect structure is formed to physically contact each of the first diffusion fin and the third diffusion fin, and wherein the gate level structure is formed to physically contact each of the first diffusion fin and the third diffusion fin, and wherein the third local interconnect structure is formed to physically contact each of the first diffusion fin and the third diffusion fin.
 12. The integrated circuit as recited in claim 11, further comprising: a fourth diffusion fin of linear shape, the fourth diffusion fin defined to extend lengthwise over the substrate in the first direction, wherein the second local interconnect structure is formed to physically contact each of the second diffusion fin and the fourth diffusion fin, and wherein the gate level structure is formed to physically contact each of the second diffusion fin and the fourth diffusion fin, and wherein the third local interconnect structure is formed to physically contact each of the second diffusion fin and the fourth diffusion fin.
 13. The integrated circuit as recited in claim 12, wherein a lengthwise centerline of the first diffusion fin is separated from a lengthwise centerline of the second diffusion fin by a diffusion fin pitch as measured in the second direction, and wherein a lengthwise centerline of the third diffusion fin is separated from the lengthwise centerline of the first diffusion fin by a first integer multiple of the diffusion fin pitch as measured in the second direction, and wherein a lengthwise centerline of the fourth diffusion fin is separated from the lengthwise centerline of the second diffusion fin by a second integer multiple of the diffusion fin pitch as measured in the second direction.
 14. The integrated circuit as recited in claim 13, wherein the first integer multiple is one and the second integer multiple is one.
 15. The integrated circuit as recited in claim 13, wherein the first integer multiple is two and the second integer multiple is one.
 16. The integrated circuit as recited in claim 13, wherein the first integer multiple is two and the second integer multiple is two.
 17. The integrated circuit as recited in claim 13, further comprising: a fifth diffusion fin of linear shape, the fifth diffusion fin defined to extend lengthwise over the substrate in the first direction, wherein the first local interconnect structure is formed to physically contact the fifth diffusion fin, and wherein the gate level structure is formed to physically contact the fifth diffusion fin, and wherein the third local interconnect structure is formed to physically contact the fifth diffusion fin.
 18. The integrated circuit as recited in claim 17, further comprising: a sixth diffusion fin of linear shape, the sixth diffusion fin defined to extend lengthwise over the substrate in the first direction, wherein the second local interconnect structure is formed to physically contact the sixth diffusion fin, and wherein the gate level structure is formed to physically contact the sixth diffusion fin, and wherein the third local interconnect structure is formed to physically contact the sixth diffusion fin.
 19. The integrated circuit as recited in claim 18, wherein a lengthwise centerline of the fifth diffusion fin is separated from the lengthwise centerline of the first diffusion fin by a third integer multiple of the diffusion fin pitch as measured in the second direction, and wherein a lengthwise centerline of the sixth diffusion fin is separated from the lengthwise centerline of the second diffusion fin by a fourth integer multiple of the diffusion fin pitch as measured in the second direction.
 20. The integrated circuit as recited in claim 19, wherein the first integer multiple is one, and the second integer multiple is one, and the third integer multiple is two, and the fourth integer multiple is two. 